When Kim Philby fled to Moscow in 1963, he became the most notorious double agent in the history of espionage. Recruited into His Majesty’s Secret Intelligence Service at the beginning of World War II, he rose rapidly in the ranks to become the chief liaison officer with the CIA in Washington after the war. When it was exposed that Philby had begun spying for the Soviet Union years before he joined the British intelligence service, he fled to Moscow one jump ahead of British agents who had come to arrest him. Robert Littell recounts the little-known story of the spy's early years through the words of Philby's friends and lovers, as well as his Soviet and English handlers as we follow the evolution of a mysteriously beguiling man who kept his masters on both sides of the Iron Curtain guessing about his ultimate loyalties.